1. Field of the Invention
The present invention relates to a method of displaying a thumbnail image, a server computer, and a client computer.
2. Description of the Related Art
According to a file server or a document management system of a client/server model, data files of a variety of formats are mixed up and stored on the server computer side. A client computer accesses the server computer as required to receive and display the image or document data of a desired data file.
Client computers of such a document management system display a list of image or document data files stored in the server computer on a display unit such as a CRT (cathode ray tube) display or an LCD (liquid crystal display).
For instance, such client computers may employ a function referred to as a thumbnail display function or an icon display function to display a list of image or document data files stored in the server computer. The thumbnail display function displays a miniature version of the image data of a data file stored in the server computer or an image into which the document data of a data file stored in the server computer is converted. The icon display function displays icons according to the types of data files. Particularly, the thumbnail display function has the advantage that the contents of all or part of the image or document data of data files stored in the server computer can be recognized at a glance.
The thumbnail display function, however, also has the following disadvantages.
First, the thumbnail display function requires a greater display area per data file than other display methods such as the icon display function. Accordingly, the number of data files displayable on one screen is limited.
More specifically, according to the thumbnail display function, generally, an image dedicated to thumbnail display (for instance, a 128×128-pixel JPEG image) is created and stored independent of a data file. In the case of performing thumbnail display for the data file, the dedicated thumbnail image is displayed, thereby increasing display speed. However, some users desire to increase the number of data files displayable on a screen by reducing the size of a thumbnail image. Meanwhile, other users are even willing to limit the number of data files displayable on a screen in order to see the contents of all or part of the image or document data of data files displayed in a list with larger images.
The technique of forming an image dedicated to thumbnail display of any size by enlarging or reducing the original image at the time of thumbnail display and the technique of previously forming and storing images dedicated to thumbnail display of a plurality of sizes separately from a data file are well known methods for solving the above-described problem, for instance. However, the former technique requires a large memory capacity and a large amount of calculation time for size reduction to form a thumbnail image. The latter technique consumes a large memory capacity in order to store a plurality of dedicated thumbnail images.
Second, according to the thumbnail display function, there is a difference in visibility among the images of data files displayed in a list depending on the types of the data files. For instance, a thumbnail image that shows an overall image may be satisfactory for a data file containing a picture image. However, thumbnail display produces little effect for data files containing, for instance, documents of a fixed format because their overall images are the same in thumbnail display.